Runners’ knees get a lift: Elevating heel cuts patellofemoral load

Wearing heel lifts in conventional running shoes can help reduce patellofemoral joint loading and may offer an alternative to gait retraining in runners with patello­femoral pain (PFP), according to research conducted at the University of Wisconsin-La Crosse.

In 16 active college-aged women without PFP, running with heel lifts was associated with a 4.2% reduction in peak patellofemoral joint stress and a 9.3% reduction in patellofemoral stress impulse, compared with running in the same shoes without heel lifts.

The findings, which were published in the October 2017 issue of the International Journal of Sports Physical Therapy, suggest a similar intervention could translate into a decrease in pain for runners with PFP, said Thomas Kernozek, PhD, FACSM, a professor of health professions at the University of Wisconsin-La Crosse and senior author of the study.

“We tested people running in the lab with and without the heel lift, and it seemed to lower patellofemoral stress, so maybe it would help people who do have some pain,” said Kernozek, who is also the director of the La Crosse Institute for Movement Science.

The study participants, all habitual rearfoot strikers, were analyzed as they ran along a walkway at a predetermined speed of 3.46 m/s. All of the women wore the same model of running shoe, with and without 11-mm heel lifts. The lifts were affixed to the shoe bed with double-sided tape and then covered with a sock liner. Kernozek said the lifts used in the study were sturdy enough that he believes they would not need to be replaced any sooner than a pair of running shoes.

Wearing the heel lifts was not associated with significant changes in stride length or cadence, and all of the participants maintained a rearfoot strike pattern. However, the heel lifts were associated with other gait changes that suggest the intervention mimics some of the effects of switching to a forefoot strike pattern, which is associated with less patellofemoral joint stress than a rearfoot strike pattern.

Initial center of pressure location was 9.1% more anterior with the heel lifts than without, and ankle dorsiflexion at initial contact was reduced by 28% with the heel lifts; both differences were statistically significant.

Gus Almonroeder, DPT, PhD, an assistant professor in the physical therapy program at Trine University in Angola, IN, said the study was long overdue.

“It’s a really good study,” Almonroeder said. “And now we understand that (heel lifts) change the mechanics enough to warrant more study. It’s a simple study, but it’s elegantly done.”

Because of the multifactorial nature of PFP, Almonroeder suggested further analyzing the study data to see if there is a specific subset of runners who saw a reduction in patello­femoral stress when wearing the heel lifts.

The simplicity of the heel-lift intervention is clinically appealing, Kernozek and Almonroeder said. Both noted that, although gait retraining programs can be effective for addressing PFP, they can be difficult to implement—at least in part because runners can be resistant to change.

“It’s really hard to change someone’s running pattern,” Almonroeder said. “A lot of people are using a metronome pattern so they take more steps, which means they naturally land on the front of the foot. You can do that training, test it in the lab and it looks good, but then you bring them back a few weeks later and they’re not doing it.”

In addition, gait changes that reduce the risk of some injuries may inadvertently increase the risk of other injuries, as the La Crosse group reported in the May 2015 issue of Medicine and Science in Sports and Exercise.